If you are one of those lucky people who doesn't feel like a light-headed piece of crap when you fast, you might not be opposed to skipping meals a few times a week. The rest of you will probably not be as excited by this possibility. But what if fasting at regular intervals could help protect your brain against illnesses like Alzheimer's and Parkinson's? Would a few days of extreme crabbiness per month be worth it?

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You might want to start pondering that question because researchers at the National Institute on Ageing in Baltimore have reported that they've found evidence showing that periods of eating virtually nothing could protect the brain against degenerative diseases and other things terrible things like strokes. It's been known for a while that low-calorie diets (also known as calorie-restricted diets) can extend lifespan—both in rats and mice and in humans. But Professor Mark Mattson, professor of neuroscience at Johns Hopkins University School of Medicine, and his team argue that it might not be necessary to be perpetually hungry to achieve the benefits of calorie restriction. Mattson explains,

Reducing your calorie intake could help your brain, but doing so by cutting your intake of food is not likely to be the best method of triggering this protection. It is likely to be better to go on intermittent bouts of fasting, in which you eat hardly anything at all, and then have periods when you eat as much as you want. In other words, timing appears to be a crucial element to this process.

In their studies, cutting daily intake to around 500 calories for two out of every seven days had clear effects. And you have to admit, if you've got to limit your calorie consumption to protect your brain, doing it only two days a week sounds a lot more tolerable than doing it all the time.

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So how could quasi-starvation be good for you for any length of time? Well, among other things, Mattson and his team have found that levels of two cellular messaging chemicals that play a role in neuron growth get a boost when you limit your caloric intake. This enhanced neuron growth could counteract the impact of degenerative diseases on your brain. While it seems counterintuitive to our modern way of looking at things—where hunger never seems beneficial, Mattson says there is an evolutionary reason behind it:

When resources became scarce, our ancestors would have had to scrounge for food. Those whose brains responded best—who remembered where promising sources could be found or recalled how to avoid predators—would have been the ones who got the food. Thus a mechanism linking periods of starvation to neural growth would have evolved.

These days we don't often have to scrounge, and we don't have to run around hunting our food anymore either, but that doesn't mean our muscles don't still need to stay active. And the same goes for our brains. In fact, Mattson likens fasting to a workout for your brain:

The cells of the brain are put under mild stress that is analogous to the effects of exercise on muscle cells. The overall effect is beneficial.

Of course, just as exercise can sometimes be extremely unpleasant, so can fasting. All you'd be eating on your two days of deprivation would be the equivalent of "a few vegetables and some tea." Ouch. It's enough to make your stomach rumble just thinking about it. But the upside is that on the other five days of the week, you get to eat whatever you like—within reason, I'm sure. And it does have definite benefits in terms of general health and even, according to Mattson, on things like asthma. And in rats there was a clear impact on the brains of rodents who had Alzheimer's and Parkinson's.

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Mattson and his team are now working on doing human fasting studies with MRIs, and if they can establish a definitive link between fasting and neuron boosting, there could soon be a practical way to optimize your brain by restricting your intake from time to time. And Mattson even swears it won't be that hard on you,

We have found that from a psychological point of view that works quite well. You can put up with having hardly any food for a day if you know that for the next five you can eat what you want.

Ugh. That still doesn't sound that fun. But perhaps they will fail to prove this once and for all, and we'll be spared a life where the odd weekend is spent eating a few carrot sticks and a cup of Earl Grey. But if not, it looks like we'll maybe have to make the painful admission that Gwyneth Paltrow and her ilk were on to something with all their fasts—though not necessarily with all those cleanses and flushes. Let's draw the line at paying money to have the entire contents of our intestines emptied out.